Summarize this article with
Avast high CPU usage usually shows up as a slow, noisy PC and a process called AvastSvc.exe (the Avast Antivirus service) near the top of Task Manager. Short spikes during scans and updates are normal. Constant high usage isn’t, and you can almost always fix it without giving up protection.
Table of Contents
Avast High CPU Usage: Why Does the Avast Service Use So Much CPU?
Antivirus software has to watch files, downloads, web traffic and running apps in real time to keep your system safe from threats. That work needs CPU time, especially during a full scan, a big definitions update or right after you install lots of new files. Problems start when that activity never settles down.
The most common causes are:
- A full or scheduled scan running while you work or play
- Two real-time antivirus tools running at once and scanning each other
- An outdated Avast version or corrupted installation
- Behavior Shield or File Shield constantly scanning a busy folder, such as a game, development or backup folder
- Extra Avast tools, like Avast Cleanup, running background maintenance
How to Fix Avast High CPU Usage on Windows 11 and 10
Work through these fixes in order. I’d check Task Manager after each one, so you know which change actually helped. Menu names below match the current Avast Free Antivirus layout; if your version looks different, the same options live under the ☰ Menu > Settings screen.
1. Check What Avast Is Doing Right Now
Open Avast and look for a running scan. If a full scan or a scheduled Smart Scan is in progress, high CPU is expected until it finishes. You can let it complete, pause it, or move scheduled scans to a time you’re usually away from the PC.
2. Update Avast and Its Virus Definitions
Old builds can carry performance bugs that later versions fix. In Avast, open ☰ Menu > Settings > General > Update and click Check for updates for both the virus definitions and the application. Restart your PC when it’s done.
3. Don’t Run Two Antivirus Programs at Once
This is the cause I’d rule out first. If you also have another paid antivirus installed, both may scan the same files over and over. Either uninstall one, or switch Avast to Passive Mode (under Settings > General > Troubleshooting) so it stops real-time scanning and lets the other product do that job. Windows Security turns its own real-time protection off automatically when Avast is active, so that pairing isn’t usually the problem.
4. Add Exceptions for Busy, Trusted Folders
If CPU jumps whenever you launch a particular game or work in a project folder, Avast may be rescanning thousands of files. Add that folder under Settings > General > Exceptions. Only do this for folders you trust, since Avast will no longer scan them.
5. Adjust Core Shields You Don’t Need
Avast’s real-time protection lives under Settings > Protection > Core Shields. If you only read email in a browser, Mail Shield adds little and can be turned off there. I wouldn’t switch off File Shield, Behavior Shield or Web Shield, since they do most of the protecting.
6. Remove Avast Cleanup or Other Extra Tools
Avast Cleanup is now a separate product rather than a built-in component, and its background maintenance can add CPU load. If you don’t use it, uninstall it from Windows Settings > Apps > Installed apps. The same goes for any Avast extras you installed and no longer need.
7. Repair the Avast Installation
A damaged install can leave the service stuck in a loop. Avast’s own repair guide walks through it: open Windows Settings > Apps > Installed apps, choose Avast Free Antivirus, click Uninstall, and select Repair when the Avast Setup window opens. Restart the PC afterwards.
8. Do a Clean Reinstall
If repair doesn’t help, uninstall Avast, run Avast’s official uninstall utility (Avast Clear) to remove leftover files, restart, and install the latest version from Avast’s website. Download installers only from the official site.
Which Fix Should You Try First?
| What you see | Likely cause | Best fix |
|---|---|---|
| CPU high for 30–60 minutes, then normal | Scan or update running | Let it finish or reschedule scans |
| CPU high all the time | Second antivirus or old version | Remove one antivirus, update Avast |
| CPU spikes when opening one game or folder | Files rescanned on every launch | Add a trusted-folder exception |
| High CPU after an update | Damaged installation | Repair, then clean reinstall |
Frequently Asked Questions
Is it safe to end AvastSvc.exe in Task Manager?
Windows usually won’t let you, because Avast protects its own service. Even if you could, it would switch off your protection. Fix the cause instead.
Will these fixes make my PC less secure?
Updating, repairing and reinstalling don’t reduce protection. Exceptions and turning off Mail Shield reduce it slightly, so use them only where they make sense.
Should I just switch antivirus?
If Avast keeps slowing an older PC after all of these fixes, trying another reputable antivirus software or relying on Windows Security is a reasonable choice. Just make sure only one real-time antivirus is active.
Also read:
